Hydraulic torque resistance devices wherein hydraulic fluid is transferred from one chamber to another through an adjustable resistance are used in exercising equipment. One such device is disclosed in my patent 4,941,554. In that machine the torque resistance device includes a rotary vane which resists rotation of the shaft to which it is mounted by forcing hydraulic fluid from a chamber on one side of the vane to a chamber on the other side of the vane. When the shaft is rotated by the person doing the exercise, the fluid is heated and expands, and unless the expanded fluid is permitted to escape from the chambers, it will leak from the device. When the fluid subsequently cools and contracts, additional fluid must be supplied to the chambers to prevent voids from forming within the chambers with a resulting irregularity in the resistance to torque provided by the device.